33 Analysis of Manufacturing Costs for Powder Metallurgy (PM) …
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33.3 Gear Manufacturing: Industrial Case Study
The chosen object for this study is a R&D 4th drive gear (a helical gearwheel) for
a M32 six-speed manual transmission gearbox used in passenger cars such as Opel
Insignia or SAAB 95 as shown in the Fig. 33.1 below. The optimized (incl. 12
weight reduction holes) P/S version of this gearwheel has not been mass-produced.
The reason for which it is chosen for this case study is the fact that some limited data
is either publically available or can be obtained through non-disclosure agreement
(NDA) from interviewed companies (Kianian 2019). Based on interviews with PM
part makers the batch size of 30,000 parts and the annual production of 400,000 parts
is selected for this analysis to prototype a real production scenario.
For the manufacturing cost calculation, at first the manufacturing process routes
for the P/S gear manufacturing were identified as illustrated in Fig. 33.2 below.
Metal powders are porous material by nature and that consequently influences quality
and tolerances of gears manufactured with metal powders due to residual porosity
(Kianian 2019). Hence, it is a common practice to introduce a second densification
process (e.g. gear rolling) to produce a final gear nearly without any porosity in the
surface (Kianian 2019; Andersson and Flodin 2017). The actual production process
routes for this study gear had not utilized gear rolling; however, it is included in
this case study. Since one of the main objective of this research project is to identify
and analyze different P/S process routes for gear production in order to compare
their final performance (e.g. strength) and quality (e.g. tolerances) to conventional
machined gears.
Main gear data
Normal module (mn) : 1.64 mm
Helix angle (β) : 32.25
o
Normal pressure angle (αn) : 16.25
o
Number of teeth (z) : 50
Fig. 33.1 a CAD model of the gearbox layout (to the right). b redesigned 4th drive gear overview
with weight reduction holes (to the left) (Larsson et al. 2014; Andersson and Flodin 2017)
Fig. 33.2 PM process routings for the case study helical gear
475
33.3 Gear Manufacturing: Industrial Case Study
The chosen object for this study is a R&D 4th drive gear (a helical gearwheel) for
a M32 six-speed manual transmission gearbox used in passenger cars such as Opel
Insignia or SAAB 95 as shown in the Fig. 33.1 below. The optimized (incl. 12
weight reduction holes) P/S version of this gearwheel has not been mass-produced.
The reason for which it is chosen for this case study is the fact that some limited data
is either publically available or can be obtained through non-disclosure agreement
(NDA) from interviewed companies (Kianian 2019). Based on interviews with PM
part makers the batch size of 30,000 parts and the annual production of 400,000 parts
is selected for this analysis to prototype a real production scenario.
For the manufacturing cost calculation, at first the manufacturing process routes
for the P/S gear manufacturing were identified as illustrated in Fig. 33.2 below.
Metal powders are porous material by nature and that consequently influences quality
and tolerances of gears manufactured with metal powders due to residual porosity
(Kianian 2019). Hence, it is a common practice to introduce a second densification
process (e.g. gear rolling) to produce a final gear nearly without any porosity in the
surface (Kianian 2019; Andersson and Flodin 2017). The actual production process
routes for this study gear had not utilized gear rolling; however, it is included in
this case study. Since one of the main objective of this research project is to identify
and analyze different P/S process routes for gear production in order to compare
their final performance (e.g. strength) and quality (e.g. tolerances) to conventional
machined gears.
Main gear data
Normal module (mn) : 1.64 mm
Helix angle (β) : 32.25
o
Normal pressure angle (αn) : 16.25
o
Number of teeth (z) : 50
Fig. 33.1 a CAD model of the gearbox layout (to the right). b redesigned 4th drive gear overview
with weight reduction holes (to the left) (Larsson et al. 2014; Andersson and Flodin 2017)
Fig. 33.2 PM process routings for the case study helical gear